The recently promoted heir to the Saudi throne, Crown Prince Mohammed bin Salman, known as M.B.S., has pledged to modernize the country. His agenda includes diversifying the Saudi economy beyond oil, expanding trade, bolstering employment and loosening restrictions on entertainment. But at least two domestic factors complicate his ambitions, and we may see them play out on the world stage in 2018.

In response to the Trump administration’s rollout of aggressive policies on immigration and travel, Farah Pandith and Ayaan Hirsi Ali­—both senior fellows with the Belfer Center’s Future of Diplomacy Project—have shared their contrasting views in media interviews.

The Orlando massacre is a hideous reminder to Americans that homophobia is an integral part of Islamic extremism. It is important to establish why a man like Omar Mateen could be motivated to murder 49 people in a gay nightclub while he proclaimed his support for Islamic State and then pray to Allah. Ayaan Hirsi Ali, Fellow of the Future of Diplomacy Project examines the connection between homophobia and the Islamic religion.

We have a problem — not a problem from hell, but one that claims to come from heaven. That problem is sometimes called radical, or fundamentalist, Islam, and the self-styled Islamic State is just its latest iteration. But no one really understands it.

In the summer of 2014, Maj. Gen. Michael Nagata, the commander of U.S. special operations forces in the Middle East, admitted as much when talking about the Islamic State. “We do not understand the movement,” he said. “And until we do, we are not going to defeat it.”

This year, with good reason, Americans have celebrated the moment 50 years ago when the struggle for civil rights for African-Americans reached a decisive moment: the 1965 March from Selma to Montgomery. The movie Selma won an Oscar. President Obama went to Selma and gave one of his finest speeches.

Since the massacre at the offices of the French satirical magazine Charlie Hebdo in January, the U.S. media has understandably devoted attention to the problem of radical Islam in Europe. The fact has been widely reported that thousands of European Union citizens have traveled to Iraq and Syria to join the self-styled Islamic State. Almost as much coverage has been given to stories of French Jews emigrating to Israel. And there have been numerous articles about Michel Houellebecq’s diabolically timed novel Soumission, which imagines France in 2022 with a Muslim president introducing sharia law and being fawned over by the Parisian establishment.

Less than a year after I moved to the United States in 2006, I was asked to speak at the University of Pittsburgh. Among those who objected to my appearance was a local imam, Fouad El Bayly, of the Johnstown Islamic Center. Mr. Bayly was born in Egypt but has lived in the U.S. since 1976. In his own words, I had “been identified as one who has defamed the faith.” As he explained at the time: “If you come into the faith, you must abide by the laws, and when you decide to defame it deliberately, the sentence is death.”

The ferment we see in the Muslim world today is not solely due to despotic political systems, and it is not solely due to failing economies and the poverty they breed. Rather, it is also due largely to Islam itself and the incompatibility of certain of that faith’s key tenets with modernity. That is why the most important conflict in the world today is between those who are hell-bent on preserving, and even increasing, these incompatibilities, and those who are bravely prepared to challenge them — not to overthrow Islam but to reform it.

“Islam’s borders are bloody,” wrote the late political scientist Samuel Huntington in 1996, “and so are its innards.” Nearly 20 years later, Huntington looks more right than ever before. According to the International Institute for Strategic Studies, at least 70% of all the fatalities in armed conflicts around the world last year were in wars involving Muslims. In 2013, there were nearly 12,000 terrorist attacks world-wide. The lion’s share were in Muslim-majority countries, and many of the others were carried out by Muslims. By far the most numerous victims of Muslim violence—including executions and lynchings not captured in these statistics—are Muslims themselves.

In Heretic: Why Islam Needs a Reformation Now, Ayaan Hirsi Ali writes that a religious reformation is the only way to end the terrorism, sectarian warfare, and repression of women and minorities that each year claim thousands of lives throughout the Muslim world. She argues that the violent acts of Islamic extremists cannot be divorced from the religious doctrine that inspires them. Instead, she says, we must confront the fact that they are driven by a political ideology embedded in Islam itself.